Search Results

Now showing 1 - 4 of 4

Some of the metrics are blocked by your
consent settings
A Geographic Object-Based Image Approach Based on the Sentinel-2 Multispectral Instrument for Lake Aquatic Vegetation Mapping: A Complementary Tool to In Situ Monitoring
(2024-03-05)
M. Tompoulidou
;
E. Karadimou
;
A. Apostolakis
;
V. Tsiaoussi
Aquatic vegetation is an essential component of lake ecosystems, used as a biological indicator for in situ monitoring within the Water Framework Directive. We developed a hierarchical object-based image classification model with multi-seasonal Sentinel-2 imagery and suitable spectral indices in order to map the aquatic vegetation in a Mediterranean oligotrophic/mesotrophic deep lake; we then applied the model to another lake with similar abiotic and biotic characteristics. Field data from a survey of aquatic macrophytes, undertaken on the same dates as EO data, were used within the accuracy assessment. The aquatic vegetation was discerned into three classes: emergent, floating, and submerged aquatic vegetation. Geographic object-based image analysis (GEOBIA) proved to be effective in discriminating the three classes in both study areas. Results showed high effectiveness of the classification model in terms of overall accuracy, particularly for the emergent and floating classes. In the case of submerged aquatic vegetation, challenges in their classification prompted us to establish specific criteria for their accurate detection. Overall results showed that GEOBIA based on spectral indices was suitable for mapping aquatic vegetation in oligotrophic/mesotrophic deep lakes. EO data can contribute to large-scale coverage and high-frequency monitoring requirements, being a complementary tool to in situ monitoring.
Some of the metrics are blocked by your
consent settings
Mediterranean temporary ponds (habitat type 3170*) in the South Aegean Archipelago islands (Greece): filling the gaps
(2023-06-27)
E. Karadimou
;
D. Kemitzoglou
;
V. Tsiaoussi
Mediterranean temporary ponds (3170*, Directive 92/43/EEC) are scattered in the South Aegean islands (Greece). Their importance for biodiversity is great; they host plant and animal species depending exclusively or to a large extent on water, and form special habitats which act as "life refuges". At the same time, they support the agricultural activities of the local residents and provide multiple benefits. In this study, we focus on the identification, delineation and mapping of the Mediterranean temporary ponds, the description of the composition of their vegetation, their structure and functions, assessment of their conservation degree and recognition of the pressures they face. The 3170* habitat type was identified, recorded and studied in 42 locations, on 10 islands. Our results indicate that, in the South Aegean, despite the adverse climatic conditions, several small temporary ponds are preserved. They have a high degree of diversity in terms of their ecological, morphological and physico-chemical features. These are often natural wetlands with a high diversity of plant species, but in several cases, humans have artificially modified their abiotic, and hence biotic, characteristics. Most temporary ponds are altered under the pressure of long-term use of water, mainly in cultivations and grazing. Excavation, embankment and road openings bring about further degradation. In places undergoing tourist development, these risks increase. Strengthening their protection efforts, especially under the pressure of change in the climatic conditions, is essential for the conservation of Mediterranean temporary ponds.
Some of the metrics are blocked by your
consent settings
A phytosociological survey of aquatic vegetation in the main freshwater lakes of Greece
(2020-05-05)
D. Zervas
;
I. Tsiripidis
;
E. Bergmeier
;
V. Tsiaoussi
This study aims to contribute to the knowledge of European freshwater lake ecosystems with updated and new information on aquatic plant communities, by conducting national-scale phytosociological research of freshwater lake vegetation in Greece. Moreover, it investigates the relationship between aquatic plant communities and lake environmental parameters, including eutrophication levels and hydro-morphological conditions. Study area: Lakes in Greece, SE Europe.
Some of the metrics are blocked by your
consent settings
Phytosociological analysis of the aquatic vegetation of the main Greek freshwater lakes. Poster presentation in 11th Symposium for European Freshwater Sciences. Zagreb, June 30 – July 5, 2019
(2019-07-03)
V. Tsiaoussi

ΕΚΒΥ

Browse

Filters

Settings

Sort By

Results per page

Search Results